LIOCERAS OPALINUM. 55 



larger, PI. XIV, figs. 3 and 4, and an adult figured by Dr. Wright, 'Lias Am.,' pi. lxxx, 

 fig. 4; secondly, a form showing slightly a wider umbilicus, and seeming to commence 

 with coarser ribs, but as the test is not well preserved little can be said on 

 this point (PI. xiv, figs. 5, 6) ; thirdly, forms which seem to be connected with 

 Lioc. opalinum and which in general proportions of umbilicus, &c, agree exactly 

 with that species, but have some tendency to show these waves or false ribs. 

 PL XIV (fig. 1 only) gives a side view which may pass for such a form, and which 

 represents those of which I am speaking except that they are thinner. PI. XIII, 

 fig. 12, shows a portion of one of them with the commencement of the lateral 

 process of the mouth-border. Then lastly d'Orbigny has figured a thicker form 

 (' Pal. franc. Ceph.,' pi. lxii, figs. 1 and 2) under the name Am. primordialis, 

 not yet obtained by me. The specimen figured PI. XIV, figs. 1 and 2, resembles 

 it in thickness, but has a much smaller umbilicus. This may possibly be the 

 young of a peculiar form, of which I have given a figure in the hope that more 

 may be procured (PI. XIV, figs. 7, 8, and 9). This form commences with fine strige, 

 and slight indications of waves, which afterwards change to somewhat coarse ribs. 

 It is certainly considerably different from either Lioc. opalinum or comptum. 



Lioc. comptum is not a common form. It occurs in the same bed with Lioc. 

 opalinum. I possess specimens from Haresfield Hill and North Nibley in 

 Gloucestershire. From Somerset I have one specimen, not well preserved, 

 labelled " Haselbury." In Dorset I have obtained a few small specimens at 

 Burton Bradstock. 1 The kindness of Mr. B. Thompson, F.G.S., has enabled me 

 to examine two very good specimens of this variety from New Duston in North- 

 amptonshire collected by himself and Mr. W. D. Crick from what is there known 

 as the Northampton Sand. Unfortunately these arrived too late to be included in 

 the plates. The intermediate forms I have obtained from Burton Bradstock, 

 Dorset, and from Stinchcombe Hill, Gloucestershire. 



PI. XIII, fig. 11, shows a young specimen of Reinecke's form. This will 

 serve for comparison with his figure and also with the specimen, fig. 6, of a young 

 Lioc. opalinum. On account of the absence of the test its ribs appear much 

 coarser than they otherwise would. PI. XIV, figs. 3, 4, represent an older 

 specimen of the same form, with a large portion of the test well preserved. Both 

 these specimens are from Burton Bradstock. PI. XIV, figs. 5, 6, represent 

 another form not well preserved, but useful for comparison with the other two 

 placed by the side of it. This is from Haresfield Hill, Gloucestershire. PI. XIII, 

 fig. 12, shows a portion of one of the forms intermediate between Lioc. comptum 

 and opalinum, showing the commencement of the termination. PI. XIV, figs. 1, 2, 

 indicate a thick form with small umbilicus and rather sharp carina. The test is 



1 At this place I have also obtained some specimens which seem to agree with Vacek's, pi. vi, 

 figs. 15 and 16, but which I think do not belong here. The material, however, is as yet insufficient. 



